What is allowable error for the data code periods in my remote?

Question:

My remote control-equipped microcontroller's data sheet says that the carrier frequency is 38 kHz, but it does not mention what the allowable error is. Neither does it say anything about an allowable error for the data code periods.

Answer:

There are no rated allowable error for the NEC format.
However, a normal variation range of about 2 kHz (5%) is assumed.

The question of how much variation can be tolerated when actually using the device depends also on the error margin on the receiving side.
Check what this margin is in your own system.
This same margin (%) can then be applied to the data code periods.